Despite the rapid expansion of options to coerce drug-dependent offenders into treatment - culminating recently in the provisions of the 2005 Drugs Act and the government's 'Tough Choices' agenda - research findings to date are equivocal about their impact in reducing crime. This paper presents UK findings from a pan-European study on this issue. The results - at both national and international levels - reveal that court-mandated clients reported significant and sustained reductions in illicit drug use and offending behaviours, and improvements in other areas of social functioning. Those entering the same treatment services through non-criminal justice routes also reported similar reductions and improvements. The implications of these findings are discussed in the context of recent policy developments.